1. Field of the Invention
The invention relates to a method for forming a relief pattern on a vinyl chloride resin sheet and to the sheet formed by the method.
2. Description of Prior Art
A variety of processes are known for forming a vinyl chloride resin compounded composition into a formed sheet. Such techniques include a calendering process wherein a vinyl chloride resin compounded composition containing a foaming agent of a well-known type is kneaded and rolled. The resulting article is then heated at such a temperature and for a length of time such that the foaming agent is decomposed.
According to yet another process, the sheet may be formed by a mechanical foaming process wherein a vinyl chloride resin compounded composition is kneaded to give a paste sol and is then mechanically agitated while blowing air therein. The resulting foam paste is applied and then thermaly gelled.
In another process, a paste sol is obtained by kneading a foaming agent-containing vinyl chloride resin. The compounded composition is applied and thermally gelled under conditions of time and decomposition temperature of the foaming agent.
Finally, in yet another process a composition is foamed by agitating a vinyl chloride resin emulsion compounded composition while blowing air therein which is applied and then thermally gelled. The foamed sheet thus obtained may be backed with a backing material such as pulp paper, asbestos paper, a fabric, a non-woven fabric, a plywood board, an iron plate or the like, as desired.